Method of removing rust



Dec. 27, 1932. F. c. BATTISTELLA 1,392,093

METHOD OF REMOVING RUST, SCALE, AND SEDIMENT FROM THE INTERIOR OF METAL SURFACES Filed D80. 10, 1929 a INVENTOR 1M CI Adz-2%,

BY a

ATTORNEY Patented Dec. 27, 1932 it UNITED STATES PATENT OFFICE FRANCIS G. BATTISTELLA, F NEW YORK, ASSIGNOR T0 SANITATION HOLD- ING CORPORATION, OF-NEW YORK, -N. Y., A CORPORATION OF DELAWARE METHOD OF REMOVING RIJ'ST, SGALE, AND SEDIMENT FROM THE INTERIOR 0F METAE SURFACES Application filed December 10, 1929. Serial No. 413,133.

My invention relates to an improved method ofremoving rust and scale from pipes, and the object of the invention is to provide a simple, effective and economical method for the purpose.

The invention has been especially designed for, and so far has formed its principal field. of usefulness in the removal of rust and scale from water systems of buildings and particularly such systems in large apartment houses where the presence of such foreign deposits may be a serious economical detriment. The invention, however, is not limited to such use and it may be effectively employed in almost any connection where it may be desirable to remove rust and scale from pipes or piping systems, as for example, railroad steam generating plantson locomotives, water and heating systems of buildings, marine heating and steam generating systemsfcooling systems for gas engines, etc.

I will describe the improved method as it will be carried out in removing rust and scale from the pipes of a hot water heating system of a large apartment house. The adaptability of the method for the removal of rust and scale in other connections will be immediately apparent therefrom.

To carry the method into effect, a suitable apparatus is necessary. This apparatus may differ widely in construction and arrangement, but in the accompanying drawing forming part hereof, I show in diagram an apparatus with which I have secured excellent results for the ferredto.

This. apparatus is mounted upon a suitable truck which is moved as close to the building as possible, and from which flexible piping leads to the heating system to be cleaned whereby solutions, water and air may be forced through the entire heating particular purpose resystem, in reversedirections, as will be pointed out hereafter.

The apparatus comprises an air compressor A of any suitable type. capable of developing a pressure sufiiciently high to overcome the hydrostatic head of water in the heating system. ,The arrangement is such that the compressed air can be forced in either direction through the heating system. Valves 1, 2 and 3 cut off the air compressor A from the rest of the apparatus.

The apparatus next comprises a pump or series of pumps B of any suitable type, capable of developing a pressure in excess of that necessary to force water or solutions used throughout the heating system in either direction. The air compressor A and pump B may be conveniently driven by electric motors or gasoline engines. Valves 4, 5 and6 permit the pump. B to be connected to or disconnected from the heating system to be cleaned.

Next, the apparatus comprises a testing tank C into which the solutions can be run during the operation for the purpose of chemmad or volumetric determination, as will be explained later.

The apparatus next comprises a filter D of any suitable type, by which the rust and scale may be removed from the circulating llquld. Valves 7, 8, 9 and 10 permit the filter to be connected to or disconnected from the rest of the apparatus.

Next, the apparatus comprises the tanks E, and G, the purpose of which will be explalned later. Valves 11, 12, 13, 14', 15, 16 and 17 permit all or any of the tanks to be connected to the rest of the apparatus or disconnected therefrom.

A valve 18 in conjunction with valve 5, permits the testing tank C to be connected or disconnected. The testing tank C, filter D and tanks E, F and G are all subjected to pressure and therefore, are closed.

The apparatus finally comprises suitable plplng, as shown, connecting the several elements of the apparatus and in which the valves referred to are located. The two ter- 90 minals of this piping are indicated at a and b and the dotted line extending between these terminals represents the heating system to be cleaned as well as flexible hose leading thereto from the apparatus on the truck.

With an apparatus such as I have described, I now proceed to carry out my improved method, as follows:

The first step is to fully drain oil' the water from the piping system, after having 100 This water is then drained ofi and measured by volume, in order that a comparison may belater made of the cubical capacity of the ing system, all valves and outlets therein being tightly closed. This air pressure is of substantial value, for instance, a static pressure of fifty (50) pounds per square inch. The compressed air in the system will disclose the presence of any leaks or faults therein. Repairs ofsuch leaks if thus disclosed, should be made before the operation progresses.

If the pressure is held in theplping system, showing absence of leaks, lead ais now opened and the air is then allowed to rush through the piping in the building through vent a-in spurts. The direction of the air is then reversed and vent b is used in the same way. The air, escaping through these two openings in the piping system, ,acts to scavenge the interior of the pipes, removes some of the rust and scale and loosens and renders less tenacious some of the remaining 0 rust and scale. Moreover, this air scavenging of thepipes, effectively carries off water, which if present would dilute and render less effective the solution used in the next step.

. Solution A (hereafter more particularly defined) is now circulated through the system from tank E by means of pump B, being forced first in one direction and then in the other. During this circulation of solution A, compressed air from compressor A is' altomatic in a sense, since the operator will be advised that cleaning has progressed suf ficiently when the test samples show that the cleaning effect in a given time is very much reduced. K

The treatment just referred to may occupy anywhere from one to eight hours, depending piping system, both before and after cleanupon the degree of congestion of the piping ing. Air" is now forced into the empty pipsystem and upon the capacity thereof. Ex-

perience has shown that the horizontal pipes in the cellar of a building are in a worse condition than the rest of the system. These horizontal pipes are first examined, before opcheck. Of course, the removal of any portion of the scale is an improvement, but best results are secured by removing substantially all the scale except that portion which is immeiiliately adjacent and adhering to the pipe wa s.

Referring now to the characteristics of solution A, I have found that a liquid solution containing an acid .of the type of phosphoric and acetic acid, under the conditions above described, will dislodge, loosen and dissolve the rust and scale to a surprising extent, thus permitting the pipes to be effectively cleaned in a very economical way. Such acids have very little corrosive effect on the metal ofthe pipes, but at the same time I prefer to add to the solution an inhibitor, hereinafter discussed,.by which any corrosive action is prevented, and the cleaning effect of the acid solution is enhanced. An example, of asolulowed to enter the system so as to agitate the li%uid therein, as I find that by so doing tion A with which I' have secured excellent the e ect of the solution in detafihingand results is: ,7 P removin the rust and scale is en ance v or cent Solutihn A, carrying with *it the rust and i ip fa .10 5 scale'in the form of a muddy sludge, passes 10 i 30 through the filter or settling tank D, by which i 6 33 gw O the solid material is removed. During this c0 0 v 2 operation, solution A passes from and returns After the ipmgfystem has been treated with to the tank E as a closed system. From time solution as a We explained, the solution 50 to time the How is diverted to the testing tank is drained: off from the cleaned pipes, and

C, from which samples may be taken to indi- 'cate whether the cleaning has progressed sufficiently:

The treatment described 1s contlnued suf- 55 ficiently long as to remove a large part of the scale from the interior of the pipe. It is not desirable to remove all of the scale, because the latter forms in more or less minute pits on the pipe'walls and to remove these pits would tend to weaken the walls of the pipe and possibly cause leaks. I find as a matter of experience, that the nearer the cleaning opera,- tion progresses to the pipe walls, the more difficult it is to remove the scale and the slower 65 theoperation. I This control is, therefore, au-

solution Bfrom tank F is then circulated back and forth in the same way. In practice I have used for solution B, a one per cent.

(1%) solution of butyric acid, although a one percent. (1%) solution of acetic acid -may be employed in which case it is desirable efi'ect. After all traces of acid have been removed in this way the system is drained "and is then filled wit 1 clear Water, which is accurately measured. A comparison between the respective volumes representing the cubical contents before and after treatment will indicate the amount of rust and scale removed and indicate to the operator the extent and completeness of the cleaning. This completesthe method and the system is now ready for use after being filled with water in the usual way.

Referring now to'the subject of inhibitors, I find that phosphoric, acetic and butyric acids all tend, in a small degree, to corrode the iron of the piping at the same time that the oxide sludge is attacked. It is important that this oxidation -should be avoided and to this end I prefer to add a trace of an inhibitor to solutions A and B. The exact reaction of the inhibitor, I'am not yet ablc-to explain. Some have been found to go into solution with the acid, others to combine with the iron oxide and still others to act as catalysers. Their efiect, however, with my improved method is very. definite; that is to say. they practically neutralize any oxidizing action of the acids used and at the sametime increase the action of those acids in removing rust and scale. These inhibitors are usually of an organic nature, although some inorganicsubstances may be employed, such as arsenic compounds, cyanamid, formaldehyde, sulphuric acid and lead. Some of the organic catalysers which may beused are glue, nicotine, ethyl alcohol, quinolin, butanol (hormal, secondaryor tertiary), pyridine and paraethylaminophenyl.

With solution I have secured excellent results with both quinoline and pyridine in \minute quantitya fraction of one per cent. The same inhibitors may be used with solution B, and, as an example, I have foundthat asmall amount ,ofia very weak solution of glue satisfactorily answers the purpose.

-. Such a solution'may be made by dissolving one quart of glue to one hundred gallons of water. y

In the foregoing, I have described my in vention in the form preferred by me, but it will be, of course, understood that it may be modified in some particulars and according to" the specific use to which it may be put;

The extent of such modifications, is indicated in the appended claims.

, What I-claim is:

' 1. The method of removing rust and scale form ,a closed pipingsystem in situ whichconsists in circulating therethrough and under pressure a solution of relatively weak acid having the capacity of attacking. and removing the rustand scale, facilitated by the erosive action of the flowing'solution, in filtering under pressure to separate thesolids removed with and by such solution and in recirculating the filtered solution under pres rust and scale,facilitated by the erosive action of the flowing solution, in filtering under pressure to separate the solids removed with and by such solution and in recirculating the filtered solution under pressure through the piping.

3. The method of removing rust and scale from a closed-piping system in situ which consists in circulating therethrough and under pressure a solution of phosphoric acid and acetic acids having the capacityof attacking and removing the rust and scale, facilitated by the erosion of the flowing solution, in filtering under pressure to separate the solids removed with and by such solution and in recirculating the filtered solution under pressure through the piping.

4. The method of removing rust and scale froma closed piping system in situ which consists in circulating therethrough and under pressure a solution of a relatively weak acid having the capacity of attacking and removing the rust and scale, facilitated by the eroe sive action of the flowing solution, in filtering under pressure to separate the solids, removed with and by such solution and in recirculating' the filtered solution under pressure through the piping, the directionof flow of the circulating solution being periodically reversed.

5. The method of removing rust and scale from a closed piping system in situ which consists in circulating therethrough and under pressure a solution of a relatively weak acidhavingthe capacity of attacking and re- ,moving rust, and scale, facilitated by the moving the rust and scale, facilitated by the erosive action of the flowing solution, such solution also containing an inhibitor for preventing the solution froin attacking the metal walls, in filtering under pressure. to separate the solids removed with and by such solution and in recirculating the refiltered solution under pressure through the piping.

7. The method of removing rust and scale from a closed piping system in 'situ which consists in circulating therethrough and under pressure a solution of a relatively weak acid having the capacity of attacking and removing the rust and scale, facilitated by the erosive action of the flowing solution, in filtering under pressure to separate the solids removed with and by such solution, in recirculating the filtered solution under pressure through the piping, in removing the acid solution from the piping, and in circulating under pressure through the piping. a slightly acid solution having an inhibitor added thereto to free the interior walls of traces of the first solution.

8. The method of removing rust and scale from a closed piping system in situ which consists in applying a static pressure of air to the closed system, in then releasing the air pressure while maintaining the flow of air through the piping to the atmosphere to blow out trapped water and effect the scavenging action, in circulating through the closed piping and under pressure a solution of a relatively weak acid having the capacity of attacking and removing the rust and scale, facilita-ted by the erosive action of the flowing solution, in filtering under pressure to separate the solids removed with and by such solution and in recirculating the. filtered solution under pressure through the piping.

9. The'method of removing rust and scale from a closed piping system in situ, which consists in circulating therethrough and un-'.

der pressure a solution of phosphoric acid, acetic acid, and butanol, having the capacity of attacking and removing the rust and scale, facilitated by the erosive action of the flowing solution, in filtering under pressure to separate the solids removed with and by such solution and in recirculating the filtered solution under pressure through the piping.

10. The method of removing rust and scale from a closed piping system in situ which consists in circulating therethrough and under pressure a solution of phosphoric acid, acetic acid, butanol and alcohol having the capacity of attacking and removing the rust and scale, facilitated by the erosive action of the flowing solution, in filtering under pressure to'separate the solids removed with and by such solution and in recirculating the filtered solution under pressure through the piping.

11. The method of from a closed piping system in situ which consists in circulating therethrough and under pressure a solution comprising approximately forty per cent phosphoric acid, ten percent acetic acid, thirty per cent butanol and twenty per cent alcohol, said solution having'the capacity of attacking and removingpthe rust and scale, facilitated by the er0-' sive action of the flowing solution, in filtering under pressure to separate the solids removed removing rust and scale the filtered solution under pressure through the piping.

12. The method of removing rust and scale from a closed piping system in situ which consists in circulating therethrough and under pressure a solution of a relatively weak acid having the capacity of attacking and removing the rust and scale, facilitated by the erosive action of the flowing solution, in filtering under pressure to separate the solids removed with and by such solution and in recirculating the filtered solution under pressurethrough the piping, the circulation of such solution being continued to the point where the encrusting material is almost but not wholly removed. 4

FRANCIS C. BATTISTELLA.

with and by such solution and in recirculating 

